operators-code-explanation.md

1:  #include <iostream>
2:  using namespace std;
3:  int main (void){
4:    int i = 1, j = 2;
5:    if (i > j && j > i) //if: i is bigger than j AND j is bigger than i ....
6:       i++;     //...then increment i by one. BUT this condition can never be true!
7:    
8:    if (i > j || j > i) //if: i is bigger than j OR j is bigger than i ....
9:       j++;     //...then increment j by one
10:
11:    if (i | j) //if result of bitwise OR operation is true...
12:      i++; //then increment i by one
13:    
14:   if (i & j) //if result of bitwise AND operation is true...
15:      j++; //then increment j by one
16:
17:   cout << i * j << endl;
18:  return 0;
19: }

First if statement (line 5):

Pseudo-code: if(1 > 2 AND 2 > 1) -> false

This statement is always false so it can be ignored.

Second if statement (line 8):

Pseudo-code: if(1 > 2 OR 2 > 1) -> true

Either 1 > 2 or 2 > 1 has to be true. In this case 2 > 1 is true so it will incrementj by one.

Integer j is now 3 and i is still at 1!

Third if statement (line 11):

Pseudo-code: if(1 | 3) -> true

This one is a bitwise OR operation:

The | (bitwise OR) in C or C++ takes two numbers as operands and does OR on every bit of two numbers. The result of OR is 1 if any of the two bits is 1

In your case we have this scenario:

   (binary)     (decimal)
j: 0011      -> 3
i: 0001      -> 1
---------------------------- <== we are doing a bitwise OR operation here
   0011      -> 3

So the result is a 3. Inside an if statement a three will be treated as true, so it will increment i by one.

Integer i is now 2 and j is still at 3!

Fourth if statement (line 14):

Pseudo-code: if(2 & 3) -> false

This one is a bitwise AND operation:

The & (bitwise AND) in C or C++ takes two numbers as operands and does AND on every bit of two numbers. The result of AND is 1 only if both bits are 1.

In your case we have this scenario:

   (binary)     (decimal)
i: 0010      -> 2
j: 0011      -> 3
---------------------------- <== we are doing a bitwise AND operation here
   0010      -> 2

So the result is a 2. Inside an if statement a two will be treated as true, so it will increment j by one.

Now we will end up with i being 2 and j being 4.

And when we multiply both integer variables we get 8 as the result!